Studies On Nutritional Physiology Of Zinc And Iron For Japanese Seabass,Lateolabrax Japonicus, And Large Yellow Croaker,Pseudosciaena Crocea R.

Feeding trials were conducted to investigate the nutritional physiology of trace minerals for the Japanese seabass, Lateolabrax japonicus and large yellow croaker, Pseudosciaena crocea R.. The dietary requirements of zinc and iron for juvenile Japanese seabass and large yellow croaker were conducted in indoor culture system. Results of the present study are presented as follows:1. A growth experiment was conducted to determine the dietary zinc requirement for juvenile Japanese seabass (initial average weight 2.24±0.05 g). Six semi-purified diets were formulated to contain 9.68, 30.63, 48.94, 91.28, 167.49 and 326.81 mg zinc ? kg diet, supplied as ZnSO4·H2O. Each diet was randomly assigned to triplicate groups of fish in flow-through rearing system, and each tank (250L) was stocked with 30 juvenile fish. Fish were fed twice daily (06:30 and 16:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 25 to 28°C, salinity from 28 to 30‰and dissolved oxygen was approximately 7 mg l?1 during the experimental period. No significant differences in survival were found among dietary treatments. Specific growth rate (SGR) significantly increased with increasing dietary zinc from 9.68 to 48.94 mg ? kg of diet (P<0.05), and then leveled off. Zinc content in the vertebrae, whole body and serum were significantly affected by dietary zinc level (P<0.05). Broken-line analysis showed that the optimum dietary zinc requirement for Japanese seabass juveniles, using SGR and vertebrae zinc content as response criteria, was 53.2 and 87.6 mg zinc ? kg diet, respectively.2. A growth experiment was conducted to determine the dietary zinc requirement for juvenile large yellow croaker (initial average weight 1.78±0.02 g). Six semi-purified diets were formulated to contain 9.68, 30.63, 48.94, 91.28, 167.49 and 326.81 mg zinc ? kg diet, supplied as ZnSO4·H2O. Each diet was randomly assigned to triplicate groups of fish in flow-through system, and each tank(200L) was stocked with 40 juvenile fish. Fish were fed twice daily (05:30 and 17:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 26.5 to 29.5°C, salinity from 25‰to 28‰and dissolved oxygen was approximately 7 mg l-1 during the experimental period. No significant differences in survival were found among dietary treatments. Specific growth rate (SGR) significantly increased with increasing dietary zinc from 9.68 to 48.94 mg ? kg of diet (P<0.05), and then leveled off. Zinc content in the vertebrae, whole body and serum were significantly affected by dietary zinc level (P<0.05). Broken-line analysis showed that the optimum dietary zinc requirement for large yellow croaker juveniles, using SGR and vertebrae zinc saturation as response criteria, was 59.6 and 84.6 mg zinc ? kg diet, respectively.3. A growth experiment was conducted to determine the dietary iron requirement for juvenile Japanese seabass (initial average weight 1.52±0.04g g). Six semi-purified diets were formulated to contain 21.14,52.02,80.87,141.93,259.70 and 495.15 mg iron ? kg diet, supplied as FeSO4·7H2O. Each diet was randomly assigned to triplicate groups of fish in flow-through rearing system, and each tank (250L) was stocked with 30 juvenile fish. Fish were fed twice daily (06:30 and 16:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 25 to 28°C, salinity from 28 to 30‰and dissolved oxygen was approximately 7 mg l?1 during the experimental period. No significant differences in survival were found among dietary treatments. Specific growth rate (SGR) significantly increased with increasing dietary iron from 21.14 to 141.93 mg ? kg of diet (P<0.05), and then leveled off. Iron content in the vertebrae, liver and serum were significantly affected by dietary iron level (P<0.05). Broken-line analysis showed that the optimum dietary iron requirement for Japanese seabass juveniles, using SGR as response criteria, was 95.2 mg iron ? kg diet.4. A growth experiment was conducted to determine the dietary iron requirement for juvenile large yellow croaker (initial average weight 1.78±0.02 g). Six semi-purified diets were formulated to contain 21.14,52.02,80.87,141.93,259.70 and 495.15 mg iron ? kg diet, supplied as FeSO4·7H2O. Each diet was randomly assigned to triplicate groups of fish in flow-through system, and each tank(200L) was stocked with 40 juvenile fish. Fish were fed twice daily (05:30 and 17:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 26.5 to 29.5°C, salinity from 25‰to 28‰and dissolved oxygen was approximately 7 mg l-1 during the experimental period. No significant differences in survival were found among dietary treatments. Specific growth rate (SGR) significantly increased with increasing dietary iron from 21.14 to 80.87 mg ? kg of diet (P<0.05), and then leveled off. Iron content in the vertebrae, liver and serum were significantly affected by dietary iron level (P<0.05). Broken-line analysis showed that the optimum dietary iron requirement for large yellow croaker juveniles, using SGR as response criteria, was 101.2 mg iron ? kg diet.